I'm assembling my first PC with a Ryzen 7 7800X3D, Gigabyte X870 Gaming WiFi6 motherboard, 32GB Corsair Vengeance RGB DDR5-6000 memory, RTX 5070, and a 1000W modular power supply. When I press the power button, the motherboard's DRAM diagnostic light stays red and the monitor receives no signal. The RAM lighting and some cooling fans turn on, but the case fans and GPU fans do not spin. The case-fan RGB flashes briefly, and the PSU fan only spins for a moment when power is switched off. What should I check first, and could this be caused by incorrectly seated memory, power connections, or a short inside the case?
3 Answers
Start with the DRAM light. Turn the system completely off, remove both memory sticks, and install a single stick in the motherboard’s recommended slot—usually A2, the second slot from the CPU. Make sure it clicks firmly into place, then try the other stick by itself if it still fails. DDR5 systems can take a while to complete memory training on the first boot, so let it sit for several minutes before shutting it down. Also verify that the 24-pin motherboard cable and the 8-pin CPU/EPS cable near the processor are fully connected. Don’t mix modular cables from another power supply.
Check the physical installation carefully: remove the motherboard and confirm there is no extra standoff beneath it, no loose screw behind the board, and no bent socket pins. Inspect the CPU socket and reseat the processor only if necessary. Confirm the cooler’s fan is connected to the CPU_FAN header, and make sure the case fan hub has both SATA power and its motherboard control cable if it requires them. Testing the board on the motherboard box is a good way to eliminate a case short.
The GPU and PSU fans not spinning does not automatically mean they’re faulty. Many modern GPUs stop their fans at low temperatures, and the PSU has a zero-RPM mode. The brief RGB flash is also consistent with the system starting and immediately failing its hardware check. Focus on getting past the DRAM diagnostic first, then connect the storage drive, case fan hub, front-panel accessories, and other extras one at a time.
If it still refuses to POST, I’d test it outside the case with only the CPU, cooler, one RAM stick, power supply, and GPU connected. That rules out a misplaced motherboard standoff or another case-related short.